How do differently armoured units relate to damage taken?

The class of armour you wear puts you in a broad category of damage soak, but our focus on individual characters allows us to have a greater granularity of stats than you find on the tabletop. As a result, you can supplement your mitigation, health, fields, etc., with accessories.

Tacticals, Assaults and Apothecaries, for example, have access to more survivability-related accessories than Aspiring Sorcerers and Warlocks.